The use of amorphous, dense, colloidal silica materials has long been desirable to provide a frictionizing effect on fibers and to increase the strength and performance of fibrous materials, such as textile yarns during weaving. Deposition of the small, dense, amorphous particles on the surface of a fibrous material promotes friction between adjacent fibers to produce an effect which might be compared to placing two pieces of sandpaper face-to-face. Luvisi U.S. Pat. No. 2,787,968, discloses in detail the effect of colloidal silica on various substrates.
However, the use of amorphous, dense, colloidal silica materials as frictionizing agents in water-based processing industries has not been widely accepted due to the inherent chemical nature of the colloidal silica itself. When water based colloidal silica is applied to an article in an aqueous process, the silica particles exist as small, discreet spheres. Upon removal of the process water, or the water carrier for the colloidal silica, the small silica particles follow their water carrier into a diminishing volume of carrier and steadily increasing silica particle concentration. When enough of the water carrier is removed, agglomeration of the colloidal particles occurs with the formation of large, very abrasive, amorphous granules. These large agglomerated silica granules are too large to provide an efficient frictionizing effect between fibers and are so abrasive that adjacent fibers may be severely weakened or cut by their action.
Vossos U.S. Pat. No. 3,629,139, and Kovarik U.S. Pat. No. 3,660,301, disclose a process for the production of organically coated colloidal silica sols which may be dispersed in non-polar organic solvents. The organosols produced by the cited teachings demonstrate the ability to be concentrated to yield dry, free-flowing, coated colloidal silica powders which may be redispersed in an organic media, and which retain the properties of the original colloidal silica. These teachings indicate that the drawbacks of agglomeration may be prevented when the colloidal silica particles have been modified by an organic surface coating and dispersed in an organic solvent. An attempt to exploit this technology in the textile industry was made based upon the teachings of Vossos and Kovarik in the cited patent references. This attempt was not commercially successful but did provide that the organically coated silicas, applied from non-polar solvents, retained their original size and shape as discreet particles without agglomeration. The coated silica particles were shown to be non-abrasive toward fiber, metal or ceramic surfaces which came into contact with the treated yarns. Due to the maintenance of the original size and shape of the colloidal silica particles, one of the most perplexing drawbacks of this treatment was that the frictionizing effect was so efficient that processing of treated fibrous material through subsequent steps was rendered very difficult. Equally important to the lack of acceptance of these materials was their incompatability with existing water based processes and a requirement for designing and installing equipment and process modifications. These changes would have made major capital commitments necessary for the use of these materials. These factors, coupled with an unattractive economic situation with the organosol in oil, made this concept unacceptable to the industry.